U.S. Pat. No. 4,314,648 issued Feb. 9, 1982 and assigned to the assignee of this invention discloses a gravity feed shelf in which low friction tracks are utilized and which are formed by an extrusion process and which are homogeneous in nature with low friction material impregnated therein.
U.S. Pat. No. 4,470,953 issued Sept. 11, 1984 and assigned to the assignee of this invention discloses and claims a process for forming a low friction plastic tract which is homogeneous and formed from a mixture of high impact polystyrene and organo polysiloxane fluid such as dimethyl, diethyl and phenymethyl siloxane and related copolymers.
U.S. Pat. No. 4,565,725 issued Jan. 21, 1986 and assigned to the assignee of this invention discloses a composite plastic track and method of making by a coextrusion process.